The present invention relates to a power circuit for an electronic apparatus and, more particularly, to a backup circuit for a power supply circuit comprising a solar battery.
As related art, a solar power supply circuit comprises a large scale integrated circuit (LSI), a solar battery, a light emitting diode (LED), a resistance R (about 10-50K ohm), a backup condenser (about 3.3-10 micro F), and two booster condensers (about 0.047-0.1 micro F). The forward voltage V.sub.f of the LED is about 1.3-1.5 V. The resistance R and the LED form a constant voltage circuit. The backup condenser is needed for preventing the LSI from malfunctioning when no power voltage is generated from the solar battery because no light is incident on the solar battery.